1. Field of the Invention
The present invention relates to a printing apparatus and a printing method.
2. Description of the Related Art
Recently, printing apparatuses which receive image data, such as page description language (PDL)-based data, from a host computer and perform a printing operation have been made available. Also, printing apparatuses capable of duplex printing and having a function to spool image data received from a host computer and manage the spooled image data have been made available (refer to, for example, Japanese Patent Laid-Open No. 2001-232902).
In general, to perform duplex printing, the printing apparatus performs printing on a first surface of a recording paper sheet, turns over the recording paper sheet, and performs printing on a second surface of the recording paper sheet (hereinafter referred to as “automatic duplex printing”). However, even a printing apparatus having such an automatic duplex printing function cannot perform the automatic duplex printing function if the paper sheet is of a thickness or a material that cannot pass through a paper transport path for turning over the paper sheet. When performing the duplex printing on such a recording paper sheet, data is printed on one of the front and back surfaces (a first surface) of a recording paper sheet and the recording paper sheet is output. Thereafter, the recording paper sheet whose one surface was printed is manually set on a manual paper tray. The remaining data is then printed on the other of the front and back surfaces (a second surface) to realize duplex printing (refer to, for example, Japanese Patent Laid-Open No. 5-11529). Hereinafter, this type of duplex printing is referred to as “manual duplex printing”.
However, when performing manual duplex printing, the known printing apparatus needs to perform the following procedures. First, a user instructs a host computer to transfer image data for one surface of a recording paper sheet to the printing apparatus via a printer driver. Upon receiving the image data for the one surface of a recording sheet, the printing apparatus performs printing on the one surface. Subsequently, the user sets the recording sheet whose one surface was printed on a manual paper tray. The user then instructs the host computer to transfer the remaining image data for the other surface of the recording paper sheet to the printing apparatus via a printer driver. Upon receiving the remaining image data for the other surface of the recording paper sheet, the printing apparatus performs printing on the other surface. Thus, in the known manual duplex printing operation, a user needs to physically carry out a manual step operation, which tends to be troublesome.
In addition, recently, some printing apparatus allow a printing job that includes image data for a plurality of pages to specify a different paper size or a different paper type for each page. However, if a print job specifies both a paper type that is allowed for automatic duplex printing (e.g., plain paper) and a paper type that is not allowed for automatic duplex printing (e.g., thick paper), a problem occurs. More specifically, the known printing apparatus cannot appropriately determine whether it performs automatic duplex printing or manual duplex printing for that printing job.